Process and apparatus for fixing fabric webs with advance feed on to the pins of tenter frames with pin rack chains



Nov. 15, 1955 A. MExER-WINDHORST ET Al. 2,723,438

PROCESS AND APPARATUS FOR FIXING FABRIC WEBS WITH ADVANCE FEED 0N TO THE PINS OF IENTER FRAMES WITH PIN RACK CHAINS Filed Feb. 5, 1954 United States Patent O vPROCESS AND APPARATUS FOR FIXING FABRIC WEBS WITH ADVANCE FEED ON TO THE PINS OF TENTER FRAMES WITH PIN RACK CHAINS August Meer-Windhorst, Hamburg, and Bruno Hanss, Unterluss, near Celle, Germany In stretching frames or tenters with chains of pins the webs of fabric to be stretched and dried are mostly fixed on the stretching frames with a certain amount of lead or advance feed and pressed on to the pin racks of the stretching chains. This advance feed means that the length of fabric fed on to the pins is greater than the actual length of the stretching chains. Thus, if this advance feed is distributed uniformly on the pins, the webs of fabric are slightly undulated or crinkled, which allows the fabric to shrink in the longitudinal direction, that is in the direction of the warp, during the process of drying on the stretching frames. That means that the fabric can become shorter by the amount which, in most cases, it would otherwise be overstretched during the preliminary treatment.

Various methods and devices are known for fixing the webs of fabric on the pin racks of the stretching chains with distribution of the extra material resulting from the advance feed. A common feature to all these known methods and devices is that the fabric is pressed on to the pin racks by means of a cylindrical brush. A characteristic of these constructions is that in most cases the edge of the fabric web to be fixed on the pins is pressed against the cylindrical brush by a rigid guide member directly in front of the point where the fabric is fed on to the pins. As the amount of friction produced between the web of fabric and the brush is greater than that produced between the web and the above mentioned rigid guide member, the fabric web is carried along by the brush which feeds it to the pin racks and presses it on to the pins thereof.

With most kinds of fabric this method of fixing the web on the pins with a certain amount of advance fee is entirely satisfactory.

However, there are a number of dierent kinds of fabrics which cause diculties if this generally employed method of xation is applied. This is due to the special dressing or impregnation or to the peculiar physical properties of the fabric itself, which cause the fabric to adhere more strongly to the above mentioned guide member with the result that the stronger adhesion to the brush which normally exists is neutralized and the web is not fed to the pin racks in a perfect manner, that is with the necessary amount of advance feed.

The present invention relates to a process and apparatus by which these objections are reliably overcome. On the one hand the adhesive friction on the stationary guide member is considerably reduced and, on the other hand, the adhesion to the brush is appreciably increased by augmenting the pressure with which the web is forced against the brush. To attain this object, compressed air is fed from below against the edge of the fabricl at the point where it should bear against the brush. In the first form of construction the guide member is 1ocated at a greater distance from the brush than in the known constructions and in the second form of construction it is at about the same distance therefrom. In the first form of construction the dynamic pressure of the compressed air is utilized to press the fabric web against the brush. It will be evident that in this case there will be scarcely any adhesion of the fabric web on the guide member. In the second form of construction a kind of pressure cushion is formed between the guide member and the edge of the web, the sliding friction between the fabric and the guide member being considerably reduced and the adhesive friction 0n the brush considerably increased by the additional pressure.

By these measures even the most difficult kinds of fabric can be fed to the pin racks of the tenter chain in a perfect manner and consequently a perfect and uniform crinkling or undulation of the fabric web is ensured. It is particularly advantageous to make the outlet orifices for the compressed air in the guide member not as simple circular bores but to provide relatively long longitudinal slots which extend in the direction in which the fabric is fed. By this means any premature clogging of the outlet apertures is av'oided.

Two embodiments of the invention are illustrated in the accompanying drawing, in which:

Fig. 1 shows in side elevation partly in section a construction with the guide member arranged at a distance from the brush,

Fig. 2 is a similar view of a construction wherein the guide member is in close proximity to the brush.

Fig. 3 is a top view, the circular brush having been left out for the sake of clarity.

In all figures of the drawing the parts are identical and designated by the same reference numerals.

1 designates the pin racks forming the tenter chain, above which a circular brush 2 is rotatably mounted so that the ends of its bristles project below the points of the pins on the racks 1. The fabric web 3 is fed to the brush 2 the bristles of which carry it along by friction and press it on to the pins of the racks 1. Directly preceding the point where the web is carried on to the racks 1 a guide member 5 is arranged which is curved to conform to the periphery of the circular brush 2.

According to the invention, this guide member 5 is hollow and has on its side facing the brush, apertures through which compressed air is blown in the direction of the arrows 6 thereby forcing the web away from the surface of the guide member 5 and against the periphery of the brush 2, with the result that the friction between the web and the guide member is decreased and the web is caused to adhere firmly to the bristles of the brush, thus constituting reliable transport of the web to the pin racks 1.

The method above described can operate satisfactorily with less accurate adjustment of the individual parts of the apparatus than was hitherto possible, because the necessary stronger adhesion of the web to the brush than to the curved guide member is no longer dependent upon the accurate spacing or adjustment of the individual parts.

By making the outlet apertures for the compressed air in the guide member 5 in the form of longitudinal slots 6a (Fig. 3) extending in the direction in which the fabric web is fed, there is no likelihood of their becoming clogged by dust, Huff or other obstructions.

We claim:

1. Process for fixing fabric webs with advance feed on to the pins of tenter frames with pin rack chains by a rotary brush, comprising blowing compressed air against the edge of the web of fabric to press it tightly against the brush at a point directly preceding the place where the brush presses the web with advance feed on to the pins of the pin racks of the tenter.

2. Apparatus for fixing fabric webs with advance feed on the pin racks of tenters, comprising in combination with the pin racks and a cylindrical brush rotatable Patented Nov. 15, 1955` above said pin racks with its bristles projecting below the points of the pins on said racks, a guide member for the web of fabric curved to conform to the periphery of said brush and arranged adjacent the point of engagement of said brush with said pin racks, said guide member being hollow and having in its surface facing said brush apertures for expelling compressed air against the underside of the web to force it away from said guide member and against said brush.

3. Apparatus as set forth in claim 2, wherein the guide member is arranged at a slight distance from the periphery of the brush to allow compressed airl to exert dynamic pressure on the web.

4. Apparatus as set forth in claim 2, wherein the guide member is arranged in close proximity to the periphery References Cited in the le of this patent UNITED STATES PATENTS 2,114,716 Kunzle Apr. 19, 1938 FOREIGN PATENTS 476,550 Great Britain Dec. 10, 1937 663,739 Germany Aug. 12, 1938 

